XAFS Investigation of Nanoparticle Formation in 64Zn+ Ion Implanted and Thermo Oxidized Si

Resumo

The single crystal CZ n-Si(100) substrates with electron concentration n_o = 5 × 10¹⁶ cm⁻³ were implanted by ⁶⁴Zn⁺ ions with dose of 5 × 10¹⁶ cm⁻² and energy of 50 keV. During implantation the ion beam current density was less than 0.5 μA/cm² to avoid the substrate magnetically heating. After implantation, the plates were subjected to isochronous for one hour heat treatment in oxygen atmosphere at temperatures from 400 up to 1000^oC with a step of 100^oC. Zn K-edge EXAFS spectra were measured in fluorescent mode. Si(111) channel-cut monochromator was used for energy scanning; energy resolution ΔE/E = 2 × 10^–4. According to Zn K-edge EXAFS data, all Zn implanted in Si at 900^oC is fully oxidized: an absolute maximum of EXAFS Fourier transform at R ~ 1.6 Å corresponds to Zn–O distance. Based on XANES data, we suggest an interaction between implanted Zn atoms and Si support.